Buzzing from passenger side behind dash when ignition on

guy1969

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Your Mercedes
1989 300se
Ever since buying this car in May when you turn on the ignition there is a buzzing noise coming from the passenger side from inside the dash it's definitely in the dash because you can't hear it outside inside the engine compartment. When you turn on the engine the noise stays but obviously you cannot hear it as well because the engine noise drounds it out, it eventually seems to stop and if the engine is fully warmed up it seems to stop when the ignition is on . Is this an issue with the car or is it normal? And what is it?
 
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guy1969

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Your Mercedes
1989 300se
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Sorry it's a 1989 300 se
 

Ken_R

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W203 2006 C230 Estate
I'm thinking perhaps moisture in a relay causing it to oscillate. When it [the relay] warms up, the oscillations go away?

I've got a similar situation with a Holiday home where, outside, there is a somewhat complicated arrangement with PIR lights that can be overridden, through a relay, that then permits patio/bulkhead lamps to illuminate. After long absences, particularly following wetter times, the relay will oscillate for a number of evenings before 'drying out'.
 

Ken_R

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W203 2006 C230 Estate
Reminds of said 'Holiday home'. Arrived there Spring one year and, because the water drain cocks are in the adjoining shed, they needed to the turned off before the supply was turned on. Except, Hornets had decided to build a nest in the roof of the shed.:(

Add to that the fact that I am allergic to stings/bites.:eek:

Fortunately, the shed had a 'vaulted' roof. (Posh shed!:)) so the hive was about 12 foot in the air. Duck down. Keep Low. Turn off the drain cocks, and scarper!:cool:

Water supply established - coffee consumed, and it was off to the local 'Bricho' to get one of those 'directional' sprays that kills hives from a safe distance.:D

The stray buggers kept coming about the house for days afterwards. They didn't even succumb to to a hefty 'twack' from a Fly Swat.:(
 

stwat

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Your Mercedes
1989 300SE
It's probably the cabin temp sensor fan/pump thingy. That's where it resides in mine and can be heard running.
 

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